1. Field of the Invention
The present invention relates to biologically active peptides, their pharmaceutically acceptable salts, and the processes for their preparation and application as therapeutic agents.
2. Discussion of the Background
In the present specification symbols and abbreviations are those commonly used in peptide chemistry (see Eur. J. Biochem. (1984) 138, 9-37). Consequently, the three-letter amino acid symbols denote the L configuration of chiral amino acids. D-amino acids are represented by small letters: e.g., ala=D-Ala. Other symbols and abbreviations used are: AA=amino acid; AcOEt=ethylacetate; AcOH=acetic acid; Bzl=benzyl; BBS=bombesin; Boc=t-butyloxycarbonyl; BuOH=butyl alcohol; CCD=counter-current distribution; DCC=N,N'-dicyclohexylcarbodiimide; dec.=decomposition; DMAP=4-dimethylaminopyridine; DMF=Dimethylformamide; Dnp=2,4-dinitrophenyl; ECC= ethylchlorocarbonate; Et.sub.2 O=diethylether; Glp=L-pyroglutamic acid; h-GRP (or p-GRP)=human (or porcine) gastrin releasing peptide; HCl/AcOH=dry HCl in anhydrous acetic acid; HOBt=1-hydroxybenzotriazole; HPLC=hight performance liquid chromatography; i.c.v.=intracerebroventricular; MeOH=methyl alcohol; m.p.=melting point; mMel=m-bis(2-chloroethyl)amino-L-phenylalanine; n.d.=not determined; NMM=N-methylmorpholine; pMel=p-bis (2-chloroethyl) amino-L-phenylalanine; OSu=N-hydroxysuccinimidyl; TFA=trifluoroacetic acid; THF=tetrahydrofuran; TLC=thin layer chromatography; Tos=p-toluenesulphonyl; TsOH=p-toluenesulphonic acid; Z=benzyloxycarbonyl.